Some image forming apparatuses such as copying machines and multifunction printers carry out, with respect to image data indicative of an image to be printed, an image process according to the type of a document and setting conditions (e.g., print density, enlarging/reducing ratio, single-side printing/double-side printing, and margin size). Further, some image forming apparatuses cause a display device to display a preview of the image to be printed, before the image is printed. Preview display may be carried out in such a manner that images to be printed are displayed one page at a time or that images to be printed are displayed at once. An example of a prior art reference relating to a copying machine and a multifunction printer for preview display is Patent Literature 1 below.
Patent Literature 1 discloses a technique for generating a preview image without enhancing edges of image data. The image processing apparatus of Patent Literature 1 includes: an image editing circuit for carrying out various processes such as trimming, painting, reducing/enlarging the size, change of color balance, and color conversion; a printer for printing (outputting) an image processed by the image editing circuit; and an image display device for displaying, before printing, a preview of the image processed by the image editing circuit. A user estimates the content of an image process to be carried out on the image to be printed and the image quality of a printed image, and sets (adjusts) parameters and modes.